Come Up On

http://www.newyorksocialdiary.com/node/1903436/print

"My son and I visited for a week but after only two days he asked, 'Mom, can we move here?' That’s not the first or last time such a question will be posed about the new New Orleans. I emphasize 'new' because the locals are emphatic: while there’s still work to be done, funds to be raised, and wounds to heal, their city, coming up on the fifth anniversary of 'the flood,' is past what they call the 'post-Katrina era.' "

Is "come up on" in this context slang? I can't find it in dictionaries.